In the manufacture of particulate materials such as thermoplastic polymers, e.g., high pressure polyethylene, it is observed that certain lots will have a desired property such as melt index which falls outside of product specifications. To provide a maximum percentage of product falling within product specifications, the manufacturer will blend a product lot having an undesirably high melt index with a product lot having an undesirably low melt index. The resulting mixed lot will have a melt index within specifications. Such lots customarily are mixed in rotary mixers and/or remelted and extruded. Such reprocessing entails high labor costs and, in addition, high energy costs when an extrusion step is employed.
In incorporating additives such as slip agents, antiblock agents, and the like into such resins, it is customary to first prepare dry blends of the resin and additive(s) and then extrude the dry blend to form the homogeneous mixture into pellets. Such processes are burdened with high labor and energy costs.